1. Field of the Invention
The present invention relates to a semiconductor apparatus having multiple double-sided electrode elements, which are located in a single semiconductor substrate, and relates to a method for manufacturing the same.
2. Description of Related Art
Some semiconductor apparatuses include a double-sided electrode element (e.g., vertical type MOS transistor element), which has a pair of electrodes respectively located on a front side and a back side of a semiconductor substrate, and which is configured so that a current flows between the pair of electrodes. It is known that a super junction (SJ) structure may improve such a double-sided electrode element in breakdown voltage and on-state resistance. The super junction structure includes, for example, a PN column region that functions as a drift region. The PN column region has multiple N type semiconductor parts and multiple P type semiconductor parts, which are adjacently and alternately arranged to each other.
JP-A-2007-13003 discloses a semiconductor apparatus that includes multiple double-sided electrode elements arranged in a semiconductor substrate having a PN column region. The above semiconductor apparatus includes an N channel MOS transistor element having N type semiconductor parts for a drift region and a P channel MOS transistor element having P type semiconductor parts for a drift region. The N channel MOS transistor element and the P channel MOS transistor element are arranged in the same semiconductor substrate.
In the semiconductor apparatus disclosed in JP-A-2007-13003, PN junction separation insulates and separates adjacent elements from each other (see FIGS. 2 and 14 in JP-A-2007-13003). The inventors however have found the following difficulties associated with improving a breakdown voltage of a double-sided electrode element. Due to the PN junction separation, it becomes difficult to decrease an area of an element separation region or narrow a width of the element separation region. It is thus difficult to downsize a semiconductor apparatus and difficult to decrease manufacturing cost of the semiconductor apparatus.
Further, a part of the PN column region serves as an element separation region of the PN junction separation. Hence, when a transient signal (e.g., noise, surge) is applied, charge balance in the PN column region may become abnormal, or in other words, a latch-up may take place in a PNPN structure. Due to the parasitic effect, a short-circuiting may take place around a source electrode.